This invention relates in general to gas generator construction and in particular to a new and useful gas generator housing construction particularly for generating gases for filling protective bags of vehicle safety systems.
Prior art gas generators in sheet-metal construction for inflatable safety bags which must withstand enormous thermal and mechanical stresses within a short period of time comprise as their main component parts a substantially circular, cylindrical reaction chamber which is bounded by a casing and a cover screwed thereto, and is equipped with a central ignition device, and a filter chamber adjoining and encircling the reaction chamber on the outside having a substantially rectangular cross section and being formed by two sheet metal parts which are flanged together and secured to the cover or the casing by locking engagement. Gas generators of this kind, however, are very heavy because of the thick-walled casing and cover needed for reasons of resistance, and they are relatively complicated and expensive in spite of the sheet metal construction, which is a serious disadvantage primarily in the large-scale production of such generators. In addition, the radially extending ports in the thin-walled sheet-metal parts bounding the filter chamber must be made, also for reasons of resistance, sufficiently small to obtain a smaller cross-sectional area and a high speed outflow of the gas, which results in locally excessive thermal and compressive stresses in the safety bag portions exposed to the pressure gas jets.
By contrast therewith in gas generators of the mentioned kind which operate with an axial pressure gas conduction and a corresponding axial tandem arrangement of the reaction and filter chambers, a high-grade mutual reinforcement of the supporting casing parts bounding the reaction chamber and, consequently, an appreciable reduction of the wall thicknesses as compared to reaction chambers having comparable dimensions is obtained by anchoring the toroidal casing and the apertured cover to the central tube and by the materially integral edge joints, preferably formed by electron-beam welds. Nevertheless, in this design, the weight proportion of the supporting casing parts in the total weight of the gas generator is undesirably high.